THE "PISCES" SUBMERSIBLE SYSTEM
G. G. Mott, B.Mech.E., C.Eng., M.R.I.N.A.*
This paper describes the experience of operating the submersible "Vickers Pisces" together with the support ship Vickers Venturer. Designed jointly by British and Canadian companies, "Pisces" is capable of operating at depths to 1100 metres.
To be a commercially viable proposition in the U.K. setting, the submersible is seen as
part of an overall system capable of operating in sea conditions normally expected in the European continental shelf areas.
Some of the demonstration tasks are described and from these the types of task at which the Pisces/Venturer System might be successful can be deduced. Descriptions are given of the major studies carried out to improve the performance of "Pisces". Attention is also given to the development of an acceptable framework of safety for underwater vehicles and their operating procedures, arising from current experience. A proposal is made for formalized procedures of approving aspects for construction, testing and operating undersea vehicles in Europe.
it is concluded that the calculated risk taken in introducing the submersible system to this country has been worthwhile. The existence of a national policy on development of underwater engineering capability is questioned.
INTRODUCTION
In 1968, when seeking an avenue of direct engagement in commercially viable underwater activities, the author's company investigated the range of submersibles then operating and con-cluded that one particular small submersible showed the most promise of being developed for the European continental shelf sea areas.
Agreement was reached with the small Canadian company International Hydrodynamics Ltd., designers and builders of "Pisces I" submersible (600 metres), for the joint design and operation of a new "Pisces" class of submersible having a depth capability of 1100 metres. Two submersibles of this new class have been built; one is operating in the U.K. and is the subject of this paper, the other is being operated in Canadian waters by IHL.
The acquisition of "Pisces" was in the nature of a research and development exercise aimed at gaining first hand knowledge of the behaviour of systems, materials and components in a deep diving environment. It was also an important requirement that a serious attempt should be made to operate "Pisces" under commercial conditions.
Against the background of a large number of submersibles built in the U.S.A., not making a commercial living, this pro-posal did not appear to be very enterprising. However, after careful analysis the conclusion was reached that either most of the existent submersibles had not been designed to operate commercially, or that they were too expensive. Presumably this was because of the aerospace industry environment in which many of them were developed. Many were designed for specific tasks for which there was little or no commercial demand.
In the main it was recognized that, at least in the initial phase, the potential customers of a U.K. submersible system would be government departments, the needs of which would fall into two categories:
research bodiesseeking an improvement in the gather-ing of information concerngather-ing the underwater environ-ment;
emergencyrecovery of valuable objects from the sea
bed.
It was considered that the more obvious commercial applications * Vickers Ltd., Shipbuilding Group
20
Delft University of Technology
Ship Hydromechanics Laboratory
Library
Mekelweg 2, 2628 CD Delft
The Netherlands
Phone: +31 15 2786873 - Fax: +31 15 2781836
such as surveying pipelines, wellhead completions, bottom sampling etc., were less likely to be commercially rewarding until the country's demands for sea bed materials and minerals reached such a level that would necessitate work in water depths at which divers operating alone, or in conjunction with -wet" vehicles, were seriously handicapped. Such applications would necessitate considerable investment in highly specialized equip-ments for which the submersible would play only a supple-mentary role. The commercial groups holding rights to the minerals would no doubt determine the direction and pace of these developments. An attempt to exploit this market would only be feasible after the submersible proved to be a practical proposition in the environmental conditions prevailing in the intended operational areas. Recent events in the North Sea suggest that the need for these services might well be closer than was previously supposed.
It was also considered that the problems to be solved to make submersible operations on the European continental shelf viable would rank in the following order:
launching and recovery in average sea states;
ability to locate key objects, the positions of which were precisely known ;
locating objects, the positions of which were unknown; accomplishment of particular tasks to the standard at least equal in cost and quality to that of a diver, taking into account tides and water turbidity;
stimulation of a supply of U.K. components suitable for the deep ocean environment.
"Pisces" was completed early in 1969 by a combined British/Canadian team and proving trials were undertaken in 800 metres of water to meet the certification requirements of the American Bureau of Shipping (the first full scale certification of such a submersible to these rules).
Subsequently "Pisces" was air transported to the U.K. and entered service in a training mode in June 1969. Since then it has completed 250 dives, totalling 600 hours of underwater operations in depths of water varying from 10 to 400 metres.
PROGRAMME OF OPERATIONS
During this period, a variety of tasks was undertaken
and these are summarized in Table I. For obvious reasons, work undertaken for U.K. defence departments is omitted.
i) iti)
TABLE I-PROGRAMME OF UNDERWATER ACTIVITIES 1969-70
The depths of dives undertaken in European waters were yell within the limits of "Pisces"; on many occasions they were yen within that of free diving. There is a considerable appeal n the use of "Pisces" by qualified people who wish to observe
he conditions for themselves, rather than obtain information
econdhand from persons with limited observation capability. ['he merit of this facility has been emphasised on a number of
)ccasions by salvage and scientific experts.
In the past there have been several examples, involving both
'hill and military aircraft, where considerable sums of money rave been expended in recovering wreckage. Notable amongst
hese are the Comets of the 1950's, the Comet which disappeared
if Crete in 1966 and, more recently, the Aer Lingus Viscount if Tuskar Rock.
The prime objective of such recoveries is to determine what tent wrong, and in this context the most significant component D recover is the flight recorder. It is also important to analyse he geometrical position of all pieces of wreckage to ascertain ' structural damage occurred before the actual crash.
Under the present methods of using trawlers to drag or rab for wreckage, the relative location of parts is lost; some
arts are not recovered, others are seriously damaged.
It has been suggested that the submersible could be adapted
to introduce a small TV camera into the flight deck or cockpit to scan the state of the instruments before a decision is made to move the wreckage. A further suggestion is that flight recorders should be fitted with "pingers- which automatically operate on
immersion in water. Some progress is believed to have been made
to include a pinger in prototypes being tested over the sea.
With this kind of application in mind, an exercise was
carried out in association with the Ministry of Technology and the BBC for "Pisces" to locate aircraft wreckage and to relay the pictures by a surface retransmission unit to a control head-quarters for live analysis by a group of experts (Fig. 1). An
out-line of this operation was demonstrated in the "Tomorrow's
World" programme on BBC television.
During 1970 a military aircraft crashed in the general area
in which the submersible was operating and the system was
temporarily attached to the naval unit carrying out the search. Although not fully equipped for the role, "Pisces- made contact with the wreckage and recorded video tapes, which were sub-sequently replayed at the accident investigation.
Also, during 1970 a survey was undertaken of the wreck of the oil rig "Constellation" which was lost during a storm in the
North Sea in October 1969, whilst under tow to Rotterdam. This particular operation was undertaken to determine the
Tasks Location No. dives Depths, ft Remarks
'resh water trials Loch Ness 18 50-820 During these trials "Pisces" achieved a
depth greater than any previously
re-corded depths in Loch Ness
Demonstration Loch Ness 6 10-600 For news and TV media
Um work Loch Ness 4 480-720 This was "Pisces" first commercial venture
in U.K. and was undertaken on behalf of a U.K. film company
Demonstration Loch Ness 20 120-765 These demonstrations were given to
in-troduce "Pisces" to possible customers
Demonstration Loch Linnhe 5 20-165 Various tasks were performed for MAFFS
Demonstrations and
sea water trials Gare Loch 13 105-165 Evaluation trials with MOD(N)
Variety of tasks and demonstrations
Oban,
Sound of Mull, Loch Morven, Firth of Lorne,
Loch Fynne
13 90-630 A series of dives under the auspices of
NERC to allow -Pisces" to be assessed by various government depts., i.e. IGS,
SMBA, NIO, MAFFS, DAFFS
lews demonstration Ramsay Bay 1 100 Undertaken for a north west newspaper
Demonstration Portland Harbour 12 50-100 Undertaken by MOD(N) and SITV
iearch and salvage North Sea 3 130-205 Operations over wreck of rig Constellation
kircraft wreck-search Lyme Bay 3 60-100
=ish research Lyme Bay, Plymouth 3 100-160 A series of trials under the sponsorship of
kircraft wreck-search Tuskar Rock 6 260-280 Mintech for Dept. Agriculture and Fish
for Scotland, White Fish Authority, Board
J/W light tests Smerwich 2 96 of Trade, Air Accident Investigation and
'ilming and U/W Atomic Weapons Research Establishment.
burning etc. K illany Bay 2 30
icampi investigations Jura Sound 3 330-360
3ipeline survey Seascale 2 68-90
k series of geological Firth of Lorne 2 535-670 NERC charter during which the deepest
surveys and Barra Head 5 300-1300 dive by "Pisces- in U.K. waters was
samples were taken Stanton Banks 1 270 undertaken
during the course Skerryvore 2 240
of these operations Canna Head 2 200-270
Rhum 2 55-300
Malog 2 370
Rona Deeps 1 1000
Hawes Bank 3 560
Isle of Muck 3 165-310
iampling and sea Looe 5 180 NIOoperations with -Pisces"
bottom investigation Mevagissey 1 120
Eddystone 3 175-230
I'Vlink Luce Bay
/
150 Continuation of MinTech operationsf wi-eckage Surface transmission unit S-urface control of submersible NENS107.
PIG. 1Transmission of underwater t.v. from sea bed feasibility of salvage. The wreck and associated wreckage was
ocated by the support ship Venturer using an excellent side scan sonar of British manufacture. This sonar unit can also be fitted to "Pisces" since the recorder is of a chemical type (the sparking type would cause atmospheric difficulties within the confines of
the submersible hull).
Although this operation took place at the time of the equinoctial gales, four dives were made in sea states 3/4 and it
was found that the rig was inverted. A record was made of
parts of the wreck but, because of the severe tidal conditions and
the hazardous state of the wreckage, an overall inspection was not
considered possible until the weather conditions were more
suitable. Whilst the exercise was not classed as a fully successful one, it did give valuable information on the future requirements for submersible vehicles suitable for working in such conditions. "Pisces" is fitted with two grabs (Fig. 2): one is large and
simple, capable of movement in one plane and designed for lifting cylindrical objects; the other is small and versatile with
five degrees of freedom and capable of lifting 230 lbs. Using the two grabs together, a wide variety of operations are feasible..
It has been found possible to make ad hoc arrangements for
gathering geological samples such as manganese modules and the taking of water samples and plankton at various depths using these grabs. The stage has now been reached where, haNing demonstrated a general capability, more effective use could be
made of "Pisces" if earlier consideration could be given by potential customers to special tool fits appropriate to their
purposes.
For one operation a small! rock drill was fitted and satisfactory
samples were obtained. One advantage of the submersible Inounted drilling device is that samples can be taken in various planes at the discretion of the operator.
In each of the scientific dives one or two scientists have
been included as observers. They carried out their own opera-tions apart from piloting and navigating the submersible.,
TIVearr SON. 1. n/0.010F9 nt.IMATION ve.w.no Pol.tf
1 FIG. 2='"Pisces II" submergible,. .:
Toinntoo RECOVERY ARV
Judging by the general tenor of comment, the availability of thi free swimming submersible as a scientific tool has considerabI enhanced the capabilities of the marine scientists in their task o gathering information concerning the continental shelf.
Some further experiments which have been carried ou
'include the underwater firing of percussion studs to assess th feasibility of fitting patches to wrecked ships and possibly as
means of getting food and air to a wrecked submarine. Th
ignition and manipulation of an oxycutting torch was success fully tried, although in this case the gases were supplied fror the surface. An ultrasonic examination of an underwater pipelin
was also carried out.
These experiments although rather crude, were ainied a
evaluating the prospects of coping with the more demandin
applications of underwater techniques from the confines of th submersible pressure hull. Enough information was gained t
indicate that feasible solutions to these problems can be develope if the need is great enough. It should be noted that during 1969-7
another "Pisces" submersible carried out, single-handed, th salvage of Emerald Straits, a 30 metre tug, from a depth c
200 metres in Vancouver harbour.
LAUNCHING AND RECOVERY
It was considered that the greatest impact on the use c submersibles would be made by solving the problem of th
launching and recovery of the submersible in sea states normall found in the European continental shelf area. The problem c handling submersibles at sea has not generally been considere
as part of the overall operational system, a factor which it i
believed contributes to the significant low usage of many America submersibles.
From the outset an answer was sought which would h
commercially viable, the basis being a support ship small enoug to be economical and yet large enough to be modified to cart the personnel associated with the submersible and custom(
scientists.
A former fisheries research vessel Of 40 metres length wt purchased and extensive alterations were made to it, includin
conversion of the fish hold into an additional accommodatio
block for 26 persons. Several concepts of the handling gear wet
considered, including travelling cranes, portal cranes, pant(
graphs and derricks. Eventually the design preference settled o the present "A" frame design (Fig. 3).
The new requirements of the Board of Trade Freeboar Regulations applicable to small ships, together with an tit expected increase in the weight of the "Pisces" submersib
(now 11 tons), imposed serious limitations on the overall weigl of the handling gear. To save weight it has proved necessai to manufacture the "A" frame in aluminium and to exercise gre care in the design of other components.
The concept of the handling gear is to use, as far as possibl
the potential energy of the sea itself to assist in the recovery
the submersible; the winch being provided with an automat
small
FIG. 3Stern of "Venturer" showing handling gear overhauling gear which keeps the hoist rope taut. An early
decision was made to use a large nylon braided rope as a single part hoist with a soft eye at the end. This decision was made on
two separate accounts:
to avoid the necessity for a heavy block to be handled by the skin diver in the water;
the nylon rope provides a means for absorbing the variable energy of the load without leading to
uncon-trollable situations.
In the event it proved necessary to use a shackle for con-necting the hoist rope to the submersible.
Fig. 4 shows diagrammatically the current version of thc
handling gear which has been successfully used in the launching
Single ny/on hoist rope Hydraulic rams
P.
OK
..,.
-
Pendant :4' frameVW! rillEctat
%AV
.. Thw,g fineFIG. 4The procedure of recovery
Main ;4' frame
23
and recovery of the submersible in sea state 4. Conditions on some occasions were reported to be closer to sea state 5 but, as the estimates are somewhat suspect (tending to be based on the
feelings of the individuals at the time in question) claims are
being reserved until corroborative measurements are obtained about the true state of the sea during operations.
A pendant 'A' frame hangs from the main 'A' frame and
this limits "Pisces" developing an uncontrollable athwartships oscillation whilst it is being lifted clear of the water. It is intended to fit a device on the base of the inverted 'A' to lock automatically with the -Pisces" hook, so that the load could be taken off the hoist rope prior to ramming the submersible on board. A suitable design has not yet been evolved but, in the interim, the require-ment has been met by using a steel wire strop fitted by the skin
diver.
An hydraulic system provides the power for lifting the load and ramming the 'A' frame in and out, energy being stored in accumulators to provide for peak periods during the operating cycle. The geometry of this system is so arranged that "Pisces" is landed on a seating welded to the deck on which it is secured
for passage. The current apparatus is designed for a safe working
load of 12 tons, for 1.5 m freeboard and an overhang of 6 m
over the stern of the vessel.
As would be expected, technique plays a large part in the recovery system and many alternatives have been investigated. The current technique is as follows:
"Pisces" surfaces and turns into wind;
Venturer (stern to wind) takes position about 60 ft from "Pisces" and wire towing line is attached to eye on the stern of -Pisces";
two guide ropes are attached to -Pisces" and Venturer moves ahead at about two knotsto ensure manoeuvra-bility of herself and "Pisces-;
"Pisces" is drawn in by a capstan until her hoist hook is 30 ft aft of Venturer and a skin diver attaches rope; lifting sequences start, the skin diver taking up a suitable position on "Pisces".
By this method the whole system is stable and under control from Venturer despite the relative movements of herself and
"Pisces-. Attention is now being given to new developments
aimed at enabling the pick up to be made without the need for
a swimmer.
The concept of the -Pisces" system consisting of the sub-mersible, the mothership and the handling gear is that it should give mobility and make available a submersible at reasonable
commercial rates of hire. The present mother ship Venturer.
whilst adequate for the purpose, has some notable faults which
would be avoided in a new vessel. These are:
a limited capacity for deck loads in meeting MOT requirements for stability;
a machinery arrangement consisting of high speed
engines driving a reversible pitch screw which is both noisy and dangerous to the submersible and swimmers: unsatisfactory handling characteristics at low speed; main engines which are obsolescent with consequent
maintenance problems.
From current experience it is considered that a 12 ton
submersible requires a support ship approximately 180 ft long
with electric main drive, for the European continental shelf
operation. Transverse propulsion units would also help such a vessel to keep correct station during diving operations.
NAVIGATION AND SEARCH
Operations during 1970 have revealed the overall
inade-quacies of available equipments to meet the needs of underwater
navigation and search. With a limited market for submersible
services it has been a deliberate policy to seek low cost solutions
to these problems rather than some of the more exotic systems
said to be availablebut for which we cannot find evidence of
successful operation. The three main problems for which solutions have been sought are:
to know where the submersible is in relation to the
mother ship at all times;
to enable the submersible to search a defined area with
Si)
the minimum possibility of missing targets within its range of visibility;
C) to locate objects, the position of which are known
approximately.
"Pisces" is equipped with its own scanning sonar set which gives a completely satisfactory performance for the location of obstructions in its path and, to a certain extent, is helpful in locating targets within the search area. Operating at 155 kHz, it has various ranges up to 3000 ft. A directional hydrophone can be fitted for missions in which it has to search for lost objects
fitted with a pinger.
A programme was undertaken to develop two navigational systems which became known as Submarine Position and Track-ing Equipment (SPATE) and Pisces Interim Navigational System (PINS). Fig. 5 illustrates the systems and problems arising from interference. - ,, ... ..., ....
75
0 - 111011111,.. I) 443, Receiver.7 kHz ,i
,
,s--Transmitter 24kHz"-7kHz48kHzI
Binaural N4.-"i" ,,./` Allikti,"- hyd ITon-
el12\
Prope//er and wavenoise triggers transponders
Marker
,
Submersible progressively moves
marker and transponder at Transponder end of lane search
Transponder triggered by PIT and U/W telephone - Interference
Acoustic radiations
H. 5Showing SPATE and PINS systems and sources of
interference
SPATE relies upon three accurately positioned transducers carried in the support ship, where the centre transducer emits 24 kHz pulses at fixed time intervals. This produces an auto-matic 48 kHz reply from a transponder on the submersible. The reply is picked up by the forward and after transducers on the support ship and, from difference in time of receipt together with a knowledge of the submersible's depth (provided by sub-mersible over UQC), bearings can be calculated. Slant range is provided as a function of the elapsed time between propagation and receipt. The initial concept was for the calculations to be done by slide rule and tables, and approximately seven minutes was required to determine the submersible's position relative to the support ship. If successful it was planned to link the
system to a small computer with graphical output.
The SPATE system allows the support ship to know the whereabouts of the submersible relative to herself and "slave" her movements by instruction over the UQC. Bearing in mind that the ship herself is not a fixed platform, and that sound
speed in water varies. SPATE is not an exact means of guiding the submersible in a bottom search.
- -
-Transponder PIT transmission iver Under-water te/e -honePINS provides an accurate means of conducting an area square search using planted reference points on the sea bed. These take the form of two transponder buoys with sinker, each
secured by a length of chain to a marker weight. They are
dropped by the support ship at known co-ordinates. The markers and transponders are layed in such a manner that a line drawn between them is parallel to the tidal flow: thus reducing sub-mersible drift error.
The submersible interrogates the transponder at 'A' (Fig. 5) and receives a return signal on binaural hydrophones. The crew read the results of the interrogation from a bearing meter and this, together with a gyro heading, enables the submersible to home on to the transponder. At the end of the leg, the submersible
advances the transponder position by two lane spaces B in
preparation for the next run on the heading toward transponder C. In a purely visual search, where it is essential to ensure that the maximum possibility exists of covering the area, visibility determines lane width and a combination of visibility and system inaccuracy determines lane length. If the object of the search is expected to "stand proud" of the sea bed and provide a reflec-tion on the scanning sonar, then lane length and width can be
increased.
Whilst both SPATE and PINS systems were perfectly
sound in principle and complementary in function (and on some occasions even worked), the transponders of both were subject to triggering by acoustics from the propeller of the mother ship, by communications with the submersible and by wave and bottom noises. This false triggering caused blanking out of sonar responses and early collapse of transponder batteries. In addition both systems have given problems which were primarily due to the failure of electronic components. Both systems have been shelved without determining whether a change of frequency or redesign of the electronics would improve matters.
Current and preferred thoughts may be summtu ized as
follows:
For location of the submersible relative to the mother
ship, the system consists of a sonar automatically scanning
desired sectors of any width operating at 180 kHz. The submersible is fitted with a transponder operating at a
frequency of 39 kHz which responds to the beam resulting
in the submersible appearing on the tracking screen as an illuminated spot.
The search system consists of transponders suspended above the sea bed on buoys which respond to the fre-quency of the sonar of the submersible. As a iesult, the transponders show up as an illuminated spot on the sub-mersible's sonar screen. The submersible pilot can under-take search patterns by either maintaining equidistant circles around a single transponder or by steering in straight lines, keeping the transponder spot at equi-distant 'X' distances on his sonar screen (suitably over-laid for his guidance).
PROPULSION
Experience during 1970 has indicated that whilst the pro-pulsion system of "Pisces" is adequate for still water conditions, it is inadequate for the tidal conditions prevalent in certain areas of the North Sea. Accordingly a means was sought of improving the propulsion efficiency of the existing "Pisces- and with it consideration of the philosophy to be used in the design of a new
submersible more suitable for operating in the North Sea.
Propulsion efficiency emerged as two separate problems: reduction of hull resistance:
improvements in the thrust of the propulsion units
without increased power consumption.
Model tests using a I / / 2 scale model (Fig. 6 (a) ) conducted in a cavitation tunnel indicated the following make-up of the resistance: Resistance* Naked hull 100 Undercarriage 140 Grab 55 Manipulator 48 343
4--iti)FIG. 6aModel in
cavitation tunnel showing present hullconfiguration
6h-Modc1 in cavitation tunnel showing various improve-ments- to hull streamlining
Various configurations of appendages were tried and that shown in Fig. 6(b) indicates an ultimate form of improved hull configuration giving a total resistance close to that of the naked hull in the previous table. The improvements which give rise to this result are:
Resistance*
Tail fairing 40
Faired undercarriage enclosing motors
and manipulators 110
Removal of grab required for special
purposes only 60
Nose fairing 15
Removal of fin 20
* Based on resistance of naked hull = 100.
This series of tests indicated a line of action which could be taken to reduce the resistance of "Pisces", some aspects of which depend on the type of mission being undertaken at the time.
Parallel with this investigation a further set of experiments was undertaken to evaluate the efficiency of the ducted fan type
of propulsion unit Fig. 7(a). Since "Pisces" has no rudder,
steering is effected by the speed control of the port and starboard
motors. The stepped control fitted to these motors proved unsatisfactory in maintaining "Pisces- on a particular heading. A new propulsion unit (Fig. 7(b)) was designed having an open
Present
Modified
FIG. 7Propulsion units
high efficiency propeller driven by a series wound d.c. motor in which stepless speed control is achieved by using thyristor controllers.
Trials with these new propulsion units have shown that, without any further streamlining of the hull, speed has markedly improved. Pending a complete redesign of the fairings, which may not be done to "Pisces", an intermediate step of fitting a tail cone and fairing in the undercarriage will be undertaken in the near future. The former raises some difficulties of clearance during handling over the stern as -Pisces" is now faced stern forward under the present launching and recovery procedures. The fairing of the skids has further attractions in reducing the chance of entanglement by ropes or nets whilst on the bottom.
To meet the special conditions of the North Sea it was considered that it might be necessary to design a submersible with a low frontal area with the distinct disadvantages of having the pilot and observer in a prone position, but propulsion trials indicate that a design is possible based on "Pisces". Providing attention is given to high efficiency propulsion pods and to the streamlining of all apendages, a submerged speed of four knots is possible with propulsion units not exceeding 12 shp. A design
based on this is shown in Fig. 8.
FIG. 8Design concept for North Sea service SAFETY OF OPERATIONS
Apart from the technical aspects described previously, considerable progress has been made towards formulating a
=
25
(a)
philosophy on the safety of underwater operations with sub-mersibles. As with many aspects of life in the technologicalage,
safety is never absolute and one is left with the problem of
defining what is an acceptable risk and what is not.
In this ,context the matter has been actively pursued in the U.S.A. where the coast guards have taken a lead in sponsoring attempts to get underwater operators to join in preparing arrange-ments for mutual assistance in cases of emergency. In addition, the American Bureau of Shipping has instituted a special com-mittee on submersibles which meets every six months to review. technical aspects of safety.
The "Pisces" submersibles have had a good record of safety. Nevertheless, in Canadian waters an exercise has been carried out to demonstrate the practicability of one submersible rescuing another from a depth of 600 m.
The low level of submersible activity in Europe at present deprives an operator of any potential source of help should his submersible get into trouble during a diving operation. There is no second submersible. in the U.K. to call upon and the only form of rescue feasible, should "Pisces" fail to surface from below 300 ft, is to drag the bottom.
Itis thereforevital to have a means of continuously tracking
the submersible from the surface. This is done by having a transponder which is triggered from the surface and indicates the position of the submersible by a definte spot on the PPI of the sonar tracking system.
The broad requirements for the safety of a submersible are: i) avoidance of projections which can become ensnared in nets or ropes which are too heavy for the submersible to lift. If such projections are necessary they must be ejectable;
"ii) ability to discharge sufficient weight to ensure an ability to surface under any damaged conditions in which the occupants remain alive;
independent means of surfacing which does not depend on the electrical power from the main battery;
iv) a life support system to enable the personnel to survive for a sufficient period for rescue facilities to be effectively
mobilized;
a capability to escape from thee submersible- in water shallow enough so to do;
Vi) an ability for the passenger to surface the submersible in the event of incapacity of the pilot.
The risks to, and the standards of, safety of the submersible should be judged against those which are acceptable in normal diving operations. Apart from the lack of an alternative vehicle of equal performance (and this we expect is a transitory phase in the U.K.) the risks are considerably less for the "Pisces" sub-mersibles. An alternative comparison could be made with light aircraft capable of carrying one or two passengers where a -similar sort of risk is involved:
mechanical failure destroying the ability to maintain height;
no external means of assisting in safe descent.; no external means of safely abandoning the machine; failure of communications which would prevent warning of hazards;
,e) sudden indisposition of the pilot.
Does anyone seriously suggest abandoning flying because of these risks?
A device is being sought With a minimal weight in water for providing supplementary buoyancy by chemical means in an emergency, acting like a balloon in the atmosphere. There is a possible chemical which seems worthy of closer investigation for the development of a rescue pack of this type. If successful, it could also be used for other applications such as a "strap on lifter" for raising weights from thc sea bottom.
CERTIFICATION AND APPROVAL
The introduction of the "Pisces" submersible to this country and its immediate use in commercial charters has Stimulated interest in the legal issues of underwater operations. It had been anticipated that a form of continuous certification of the safety ,aspects of the submersible itself would be required and an
26
application was made to the American Bureau of Shipping for their certification. "Pisces" was the first submersible to be built and tested to the certification of ABS.
It is interesting to recount that prior applications to the Board of Trade and Lloyd's Register revealed an interest in the special requirements of submersibles, but a total unpreparedness for certification. Clearly, with the prospect of a number of sub-mersibles, undersea habitats, sea bed vehicles and sea sledges operating in the European continental shelf area in the next few
years, there is an urgent need for the setting of acceptable standards of engineering applicable to them and a means of receiving official approval of the overall parameters of design.
An analogy can be drawn by comparison with the surface ships where Lloyd's Register sets down the standards of engineer-ing coverengineer-ing materials, scantlengineer-ings and provengineer-ing tests; whereas the Board of Trade rules govern such things as free board,
prevention of fire at sea, bulkhead sub-division, damage stability,
etc.parameters of basic design which naval architects are
required to observe. Likewise, builders of submersibles should be expected to work to rules governing the integrity of the pressure hulls, penetrations, windows, electrics, hydraulics, as well as observing good practice in respect of the provisions for life support systems, reserves of buoyancy and means of coping with emergencies, etc.
As indicated in the early part of this paper, most of the work undertaken by "Pisces" has been with one government sponsored organization or another. This has stimulated the submarine branch of the Royal Navy to take an interest in the operational development of commercial submarining in this country, at least in the context of the use of such vessels by government departments. The Royal Navy has taken the view that the Submarine Service is the only professional submarine body in the country able to advise on the standards of opera-tional procedure and competence, and has accordingly sought official appointment in that role.
A near parallel can be drawn with the situation in the U.S.A. where the U.S. Navy has its own submersible capability and issues special rules for the quatification of submersibles and operating crews for the carrying of U.S. Naval Personnel.
Until now the employment of submersible vehicles in the U.K. in a private capacity has been in the nature of wishful thinking, but it is now apparent that the U.K.'s industrial survival may depend increasingly on them for the exploitation of the resources of sea areas adjacent to it. Accordingly, the emergence of an authoritive control body is to be encouraged; whether or not it should be a supplementary activity of the Naval Submarine Service is open to some doubt for the following reasons:
1) submersibles operate either on the surface or on the bottom, almost never in mid-water in depths greater than the collapsed depth which is normal for submarines; .2) submersibles operate as part of the surface ship system, and therefore the philosophy of operation is entirely different;
submariner's tend to be technical or navigational specia-lists and rarely achieve an all round engineering and operating capability. (In the present state of the art, the submersible pilot must be both a competent operator and maintainer of his vehicle and equipment.)
the scale of the operational requirements of submersiblesi is so different to that of military submarines that there is a danger of requirements being set from an entirely incorrect standpoint.
Despite the reasons for doubt, there is obviously a significant
degree of commonality with submarine operations and one hopes that a common point of view can be reached which will enable the submersible system to be developed as an industrial tool without having to meet crippling and unrealistic requirements. This matter is of vital interest to all bodies in the U.K. with ideas of utilizing submersible vehicles in extending their present capabilities as well as to those who have direct interest in supply-ing the future market needs for equipment. As is underlined in the U.S.A. experience, submersible services will not prosper if the construction of equipment is undertaken by, or is forced into, an unnecessarily expensive environment.
CONCLUSIONS
It is considered that the calculated risk in introducing a ubmersible system to this country as a commercial operation as been successful. The encouragement which has been
forth-oming from various marine authorities, which see in the 'Pisces" system a means of augmenting their respective tasks, .ugurs well for its future development.
A submersible system cannot in any way be considered a heap facility and commercial development should therefore )e cautious. More constructive progress will be made by short teps. building progressively on existing knowledge and expertise; earning from experience what is commercially acceptable and
what is not, rather than by attempting dramatic projects which have doubtful commercial value.
The U.K. with its depleted land resources may more and more be dependent on the successful exploitation of new re-sources found within its immediate subsea areas. Continental countries such as France and Germany appear to have recognized the importance of this source of new materials and are taking steps on a national basis to ensure that their interests in it are not dependent on equipment supplied from the U.S.A. It is still questionable whether we in this country have yet formu-lated a clear policy of development for serious work on the sea bed.
